1. Field of The Invention
The invention relates to an improvement in a group III nitride compound semiconductor light emitting element suitable for use in information display apparatuses such as traffic signal light apparatuses.
2. Related Art
Japanese Patent Laid-Open No. 110692/1999 discloses a light emitting element for use in a signal light apparatus. In this prior art technique, a blue light emitting element is used in combination with a green light emitting element to emit light (blue-green color light) of a blue light lamp in a signal light apparatus. The combined use of the blue light emitting element and the green light emitting element enables even a person suffering from defective color vision due to a green cone defect to perceive lighted state/unlighted state of the blue-light lamp. This is because the person suffering from defective color vision due to a green cone defect can perceive light from the blue light emitting element in the blue-light lamp.
Only rare persons among the persons suffering from a blue cone defect cannot perceive blue light. Specifications and the like established by the Metropolitan Police Department prescribe that the color of light emitted from the blue-light lamp should be a blue-green color.
In the conventional blue-light lamp, light emitted from the blue light emitting element and light emitted from the green light emitting element should be balanced with each other for meeting the specifications and the like established by the Metropolitan Police Department. To this end, the individual light emitting elements should be accurately assembled respectively in previously designed positions. Therefore, care should be taken in assembling the light emitting elements. This renders assembling work troublesome.